WO2024209727A1 - Terminal device, base station device, and method - Google Patents

Abstract

This terminal device that communicates with a base station device receives signaling from the base station device, performs Packet Data Convergence Protocol (PDCP) data recovery in accordance with the signaling, if the signaling includes a first parameter, configures a first setting on the basis of the inclusion of the first parameter in the signaling, determines whether the first setting has been set, and if it is determined that the first setting has been set for the PDCP data recovery, retransmits all previously submitted PDCP Protocol Data Units (PDU) to a Radio Link Control (RLC) entity.

Description

Terminal device, base station device, and method

The present invention relates to a terminal device, a base station device, and a method.
This application claims priority to Japanese Patent Application No. 2023-062287, filed in Japan on April 6, 2023, the contents of which are incorporated herein by reference.

The 3rd Generation Partnership Project (3GPP [registered trademark]), a standardization project for cellular mobile communication systems, is conducting technical studies and formulating standards for cellular mobile communication systems, including wireless access, core networks, and services.

For example, 3GPP has begun technical discussions and standardization of E-UTRA (Evolved Universal Terrestrial Radio Access) as a radio access technology (Radio Access Technology: RAT) for 3.9G and 4G cellular mobile communication systems. 3GPP is currently conducting technical discussions and standardization of E-UTRA extension technologies. E-UTRA is also known as Long Term Evolution (LTE: registered trademark), and the extension technology is sometimes referred to as LTE-Advanced (LTE-A) and LTE-Advanced Pro (LTE-A Pro).

In addition, 3GPP has begun technical studies and standardization of NR (New Radio, or NR Radio access) as a radio access technology (Radio Access Technology: RAT) for cellular mobile communication systems for the 5th generation (5G). 3GPP is currently conducting technical studies and standardization of NR extension technologies.

3GPP TS 38.331 v17.3.0," NR; Radio Resource Control (RRC) protocol specification" pp70-116,pp218-223,pp316-1107 3GPP TS 38.321 v17.1.0, "NR; Medium Access Control (MAC) protocol specification" pp17-104 3GPP TS 38.213 v17.1.0, "NR; Physical layer procedures for control" pp14-20 3GPP TS 38.351 v17.1.0, "NR; Sidelink Relay Adaptation Protocol (SRAP) Specification" 3GPP TS 38.322 v17.1.0, "NR; Radio Link Control (RLC) protocol specification" pp13-30 3GPP TS 38.323 v17.1.0, "NR; Packet Data Convergence Protocol (PDCP) specification" pp13-20,pp33-39 3GPP TS 38.300 v17.2.0, “NR; NR and NG-RAN Overall Description” pp43-44,pp166-175

In 3GPP, a technology called sidelink (SL) is being considered as an extension technology of NR, which allows terminal devices to communicate directly with each other without going through the core network. In addition, studies have begun on a technology called UE-to-Network Relay (U2N Relay), in which a relay terminal device provides communication via sidelink, allowing terminal devices to communicate with base station devices via the relay terminal device, as well as on enhancing service continuity in U2N Relay.

One aspect of the present invention was made in consideration of the above circumstances, and one of its objectives is to provide a terminal device, a base station device, a method, and an integrated circuit that can efficiently perform communication control.

In order to achieve the above objective, one aspect of the present invention takes the following measures.

(1) In a first aspect of the present invention, a terminal device communicating with a base station device includes a receiving unit that receives signaling from the base station device, and a processing unit, and the processing unit performs Packet Data Convergence Protocol (PDCP) data recovery in accordance with the signaling, and if the signaling includes a first parameter, performs a first setting based on the inclusion of the first parameter in the signaling, and determines whether the first setting is set, and if it is determined in the PDCP data recovery that the first setting is set, retransmits all PDCP Protocol Data Units (PDUs) previously submitted to a Radio Link Control (RLC) entity.

(2) In a second aspect of the present invention, a base station device communicating with a terminal device includes a transmitting unit that transmits signaling to the terminal device, and a processing unit, and the processing unit causes the terminal device to perform Packet Data Convergence Protocol (PDCP) data recovery in accordance with the signaling, to perform a first setting by including the first parameter in the signaling, to determine whether the first setting is set, and to determine in the PDCP data recovery that the first setting is set, thereby causing the terminal device to retransmit all PDCP Protocol Data Units (PDUs) previously submitted to a Radio Link Control (RLC) entity.

(3) A third aspect of the present invention is a method for a terminal device communicating with a base station device, comprising the steps of receiving signaling from the base station device, performing Packet Data Convergence Protocol (PDCP) data recovery in accordance with the signaling, and, if the signaling includes a first parameter, performing a first setting based on the inclusion of the first parameter in the signaling, and determining whether the first setting is set, and, if it is determined in the PDCP data recovery that the first setting is set, retransmitting all PDCP Protocol Data Units (PDUs) previously submitted to a Radio Link Control (RLC) entity.

These comprehensive or specific aspects may be realized as a system, device, method, integrated circuit, computer program, or recording medium, or as any combination of a system, device, method, integrated circuit, computer program, and recording medium.

According to one aspect of the present invention, it is possible to provide a terminal device, a base station device, and a method that realize efficient communication control processing.

1 is a schematic diagram of a communication system according to an embodiment of the present invention. A diagram showing an example of a protocol configuration for NR sidelink communication in this embodiment. A diagram showing an example of a protocol configuration for NR sidelink communication in this embodiment. FIG. 13 is a diagram showing an example of a protocol configuration in a discovery procedure according to the embodiment; FIG. 2 is a block diagram showing the configuration of a terminal device according to the embodiment. FIG. 2 is a block diagram showing the configuration of a base station device according to the embodiment. FIG. 1 is a diagram showing an example of a protocol configuration in NR according to this embodiment. A diagram of an example of the protocol configuration of the control plane of an L2 U2N relay in this embodiment. A diagram of an example of a user plane protocol configuration of an L2 U2N relay in this embodiment. 4 is an example of processing according to the present embodiment.

This embodiment will be described in detail below with reference to the drawings.

In this embodiment, the names of each node and entity and the processing in each node and entity when the radio access technology is NR are described, but this embodiment may be applied to other radio access technologies. The names of each node and entity in this embodiment may be different names.

FIG. 1 is a schematic diagram of a communication system according to this embodiment. Note that the functions of each node, radio access technology, core network, interface, etc. described using FIG. 1 are only some of the functions closely related to this embodiment, and the system may have other functions.

E-UTRA may be a radio access technology. E-UTRA may also be an air interface between UE 122 and ng-eNB 100. The air interface 112 between UE 122 and ng-eNB 100 may be referred to as a Uu interface. The ng-eNB (ng E-UTRAN Node B) 100 may be an E-UTRAN base station device. The ng-eNB 100 may have the E-UTRA protocol described below. The E-UTRA protocol may be composed of the E-UTRA User Plane (UP) protocol described below and the E-UTRA Control Plane (CP) protocol described below. The ng-eNB 100 may terminate the E-UTRA user plane protocol and the E-UTRA control plane protocol for UE 122. The radio access network composed of eNBs may be referred to as E-UTRAN.

NR may be a radio access technology. NR may also be an air interface between UE 122 and gNB 102. The air interface 112 between UE 122 and gNB 102 may be referred to as a Uu interface. gNB (g Node B) 102 may be an NR base station device. gNB 102 may have the NR protocol described below. The NR protocol may be composed of the NR User Plane (UP) protocol described below and the NR Control Plane (CP) protocol described below. gNB 102 may terminate the NR user plane protocol and the NR control plane protocol for UE 122.

Note that the interface 110 between the ng-eNB 100 and the gNB 102 may be called an Xn interface. The ng-eNB and the gNB may be connected to the 5GC via an interface called an NG interface (not shown). The 5GC may be a core network. One or more base station devices may be connected to the 5GC via an NG interface.

The state in which a connection to a base station device can be made only via the Uu interface may be called Inside NG-RAN Coverage or In-Coverage (IC). Furthermore, the state in which a connection to a base station device cannot be made only via the Uu interface may be called Outside NG-RAN Coverage or Out-of-Coverage (OoC). The air interface 114 between UE122 and UE122 may be called a PC5 interface. Communication between UE122 that is performed via the PC5 interface may be called sidelink (SL) communication. Furthermore, a terminal device capable of sidelink communication may be called a terminal device capable of sidelink communication.

In the following description, the ng-eNB100 and/or the gNB102 are also referred to simply as base station devices, and the UE122 is also referred to simply as terminal devices or UEs. The PC5 interface is also referred to simply as PC5, and the Uu interface is also referred to simply as Uu.

Sidelink is a technology that allows direct communication between terminal devices via PC5, and sidelink transmission and reception on PC5 is performed inside and outside NG-RAN coverage.

NR SL communication has three transmission modes, and SL communication is performed in one of the transmission modes with a pair of a source Layer-2 identifier (Source Layer-2 (L2) ID) and a destination Layer-2 identifier (Destination Layer-2 (L2) ID). The source Layer 2 identifier and destination Layer 2 identifier may also be referred to as the source L2 ID and destination L2 ID, respectively. The three transmission modes are "unicast transmission", "groupcast transmission", and "broadcast transmission". The transmission modes may also be referred to as cast types, etc.

Unicast transmission is characterized by (1) support for one PC5-RRC connection between a paired UE, (2) transmission and reception of control information and user traffic between UEs on the sidelink, (3) support for sidelink HARQ feedback, (4) transmit power control on the sidelink, (5) support for RLC AM, and (6) radio link failure detection for the PC5-RRC connection.

　Groupcast transmission is also characterized by (1) sending and receiving user traffic between UEs belonging to a sidelink group, and (2) supporting sidelink HARQ feedback.

Broadcast transmissions can also be characterized as (1) sending and receiving user traffic between UEs on the sidelink.

FIGS. 2 and 3 are diagrams showing an example of a protocol architecture for NR sidelink communication according to this embodiment. Note that the functions of each protocol described using FIG. 2 and/or FIG. 3 are some of the functions closely related to this embodiment, and may have other functions. Note that in this embodiment, a sidelink (SL) may be a link between terminal devices.

Figure 2(A) is a diagram of the protocol stack of the control plane (CP) for SCCH using RRC configured on the PC5 interface. As shown in Figure 2(A), the control plane protocol stack for SCCH using RRC may be composed of PHY (Physical layer) 200, which is the wireless physical layer, MAC (Medium Access Control) 202, which is the medium access control layer, RLC (Radio Link Control) 204, which is the radio link control layer, PDCP (Packet Data Convergence Protocol) 206, which is the packet data convergence protocol layer, and RRC (Radio Resource Control) 208, which is the radio resource control layer. Figure 2(B) is a diagram of the protocol stack of the control plane for SCCH using PC5-S configured on the PC5 interface. As shown in Figure 2(B), the control plane protocol stack for SCCH using PC5-S may be composed of PHY (Physical layer) 200, which is the wireless physical layer, MAC (Medium Access Control) 202, which is the medium access control layer, RLC (Radio Link Control) 204, which is the radio link control layer, PDCP (Packet Data Convergence Protocol) 206, which is the packet data convergence protocol layer, and PC5-S (PC5 Signalling) 210, which is the PC5 signaling layer.

Figure 3(A) is a diagram of the control plane protocol stack for SBCCH configured on the PC5 interface. As shown in Figure 3(A), the control plane protocol stack for SBCCH may be composed of PHY (Physical layer) 200, which is the radio physical layer, MAC (Medium Access Control) 202, which is the medium access control layer, RLC (Radio Link Control) 204, which is the radio link control layer, and RRC (Radio Resource Control) 208, which is the radio resource control layer. Figure 3(B) is a diagram of the user plane (User Plane: UP) protocol stack for STCH configured on the PC5 interface. As shown in Figure 3(B), the control plane protocol stack for the STCH may be composed of PHY (Physical layer) 200, which is the radio physical layer, MAC (Medium Access Control) 202, which is the medium access control layer, RLC (Radio Link Control) 204, which is the radio link control layer, PDCP (Packet Data Convergence Protocol) 206, which is the packet data convergence protocol layer, and SDAP (Service Data Adaptation Protocol) 310, which is the service data adaptation protocol layer.

The AS (Access Stratum) layer may be a layer including some or all of PHY200, MAC202, RLC204, PDCP206, SDAP310, and RRC208. Also, PC5-S210 and Discovery400, which will be described later, may be layers higher than the AS layer.

In this embodiment, the terms PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), SDAP (SDAP layer), RRC (RRC layer), and PC5-S (PC5-S layer) may be used. In this case, PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), SDAP (SDAP layer), RRC (RRC layer), and PC5-S (PC5-S layer) may respectively be the PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), SDAP (SDAP layer), RRC (RRC layer), and PC5-S (PC5-S layer) of the NR sidelink protocol. Note that when sidelink communication is performed using E-UTRA technology, the SDAP layer may not be required. To clarify that it is a protocol for sidelink, for example, RLC may be expressed as sidelink RLC, and other protocols may be expressed as protocols for sidelink by adding "sidelink", "SL", or "PC5" to the beginning.

In addition, in this embodiment, when distinguishing between E-UTRA protocols and NR protocols, PHY, MAC, RLC, PDCP, and RRC may be referred to as E-UTRA PHY or LTE PHY, E-UTRA MAC or LTE MAC, E-UTRA RLC or LTE RLC, E-UTRA PDCP or LTE PDCP, and E-UTRA RRC or LTE RRC, respectively. PHY, MAC, RLC, PDCP, and RRC may also be described as E-UTRA PHY or LTE PHY, E-UTRA MAC or LTE MAC, E-UTRA RLC or LTE RLC, E-UTRA PDCP or LTE PDCP, and E-UTRA RRC or LTE RRC, respectively. Additionally, when distinguishing between E-UTRA protocols, sidelink protocols, and NR protocols, PHY, MAC, RLC, PDCP, and RRC are sometimes referred to as PHY for NR, MAC for NR, RLC for NR, RLC for NR, and RRC for NR, respectively. Additionally, PHY, MAC, RLC, PDCP, and RRC are sometimes referred to as NR PHY, NR MAC, NR RLC, NR PDCP, and NR RRC, respectively.

　The following describes entities in the AS layer of E-UTRA, NR, and/or sidelink. An entity having some or all of the physical layer functions may be called a PHY entity. An entity having some or all of the MAC layer functions may be called a MAC entity. An entity having some or all of the RLC layer functions may be called an RLC entity. An entity having some or all of the PDCP layer functions may be called a PDCP entity. An entity having some or all of the SDAP layer functions may be called an SDAP entity. An entity having some or all of the RRC layer functions may be called an RRC entity. The PHY entity, MAC entity, RLC entity, PDCP entity, SDAP entity, and RRC entity may be referred to as PHY, MAC, RLC, PDCP, SDAP, and RRC, respectively. Furthermore, each entity in the AS layer may be a common entity for E-UTRA, NR, and/or sidelink, or may be an independent entity.

In addition, data provided from MAC, RLC, PDCP, and SDAP to lower layers, and/or data provided from lower layers to MAC, RLC, PDCP, and SDAP may be referred to as MAC PDU (Protocol Data Unit), RLC PDU, PDCP PDU, and SDAP PDU, respectively. Data provided from higher layers to MAC, RLC, PDCP, and SDAP, and/or data provided from MAC, RLC, PDCP, and SDAP to higher layers may be referred to as MAC SDU (Service Data Unit), RLC SDU, PDCP SDU, and SDAP SDU, respectively. In addition, a segmented RLC SDU may be referred to as an RLC SDU segment.

Here, the base station device and the terminal device exchange (send and receive) signals in the higher layer on the Uu interface. The higher layer may be referred to as the upper layer, and the terms may be interchangeable. For example, the base station device and the terminal device may send and receive RRC messages (also referred to as RRC signaling) in the Radio Resource Control (RRC) layer. The base station device and the terminal device may also send and receive MAC Control Elements (MAC CE) in the Medium Access Control (MAC) layer. The RRC layer of the terminal device acquires system information reported from the base station device. Here, the RRC message, system information, and/or MAC control elements are also referred to as higher layer signals (higher layer signaling) or higher layer parameters (higher layer parameters). Each of the parameters included in the higher layer signals received by the terminal device may be referred to as a higher layer parameter. For example, in PHY layer processing, a higher layer means a higher layer as seen from the PHY layer, and may mean one or more of the MAC layer, RRC layer, RLC layer, PDCP layer, NAS (Non Access Stratum) layer, etc. For example, in MAC layer processing, a higher layer may mean one or more of the RRC layer, RLC layer, PDCP layer, NAS layer, etc.

Terminal devices also exchange (transmit and receive) signals at the higher layer on the PC5 interface. Terminal devices may transmit and receive RRC messages (also referred to as RRC signaling) at the Radio Resource Control (RRC) layer. Terminal devices may also transmit and receive MAC Control Elements (MAC CE) at the Medium Access Control (MAC) layer. Here, RRC messages and/or MAC control elements are also referred to as higher layer signals (higher layer signaling) or higher layer parameters (higher layer parameters). Each of the parameters included in the higher layer signals received by a terminal device may be referred to as a higher layer parameter. For example, in PHY layer processing, a higher layer means a higher layer from the perspective of the PHY layer, and may mean one or more of the MAC layer, RRC layer, RLC layer, PDCP layer, PC5-S layer, Discovery layer, etc. For example, in MAC layer processing, a higher layer may mean one or more of the RRC layer, RLC layer, PDCP layer, PC5-S layer, Discovery layer, etc.

Hereinafter, the meaning of "A is given (provided) by the upper layer" or "A is given (provided) by the upper layer" may mean that the upper layer (mainly the RRC layer or the MAC layer, etc.) of the terminal device receives A from a base station device or another terminal device, and the received A is given (provided) from the upper layer of the terminal device to the physical layer of the terminal device. For example, in a terminal device, "upper layer parameters are provided" may mean that an upper layer signal is received from a base station device or another terminal device, and the upper layer parameters included in the received upper layer signal are provided from the upper layer of the terminal device to the physical layer of the terminal device. Setting upper layer parameters in a terminal device may mean that the upper layer parameters are given (provided) to the terminal device. For example, setting upper layer parameters in a terminal device may mean that the terminal device receives an upper layer signal from a base station device or another terminal device, and the received upper layer parameters are set in the upper layer. However, setting upper layer parameters in a terminal device may include setting default parameters that are given in advance to the upper layer of the terminal device. When describing the transmission of an RRC message from a terminal device to a base station device or another terminal device, the expression "submitting a message from the RRC entity of the terminal device to a lower layer" may be used. In a terminal device, "submitting a message to a lower layer" from the RRC entity may mean submitting a message to the PDCP layer. In a terminal device, "submitting a message to a lower layer" from the RRC layer may mean submitting to the PDCP entity corresponding to each SRB, since RRC messages are transmitted using SRBs (SRB0, SRB1, SRB2, SRB3, etc.). When the RRC entity of the terminal device receives an indication from a lower layer, the lower layer may mean one or more of the PHY layer, MAC layer, RLC layer, PDCP layer, etc.

An example of the PHY functions will be described. The PHY of a terminal device may have the function of transmitting and receiving data transmitted via a sidelink (SL) physical channel with the PHY of another terminal device. The PHY may be connected to a higher MAC via a transport channel. The PHY may pass data to the MAC via the transport channel. The PHY may also be provided with data from the MAC via the transport channel. In the PHY, a Radio Network Temporary Identifier (RNTI) may be used to identify various control information.

Here, we will explain physical channels. The physical channels used for wireless communication between a terminal device and another terminal device may include the following physical channels:

PSBCH (Physical Sidelink Broadcast CHannel)
PSCCH (Physical Sidelink Control CHannel)
PSSCH (Physical Sidelink Shared CHannel)
PSFCH (Physical Sidelink Feedback CHannel)

PSBCH may be used to notify the terminal device of system information required.

The PSCCH may be used to indicate resources and other transmission parameters related to the PSSCH.

The PSSCH may be used to transmit data and control information regarding HARQ/CSI feedback to other terminal devices.

The PSFCH may be used to carry HARQ feedback to other terminal devices.

An example of the functions of the MAC is described below. The MAC may be called a MAC sublayer. The MAC may have the function of mapping various logical channels to corresponding transport channels. The logical channels may be identified by a logical channel identifier (Logical Channel Identity, or Logical Channel ID). The MAC may be connected to the higher-level RLC via a logical channel. Depending on the type of information being transmitted, the logical channels may be divided into a control channel that transmits control information and a traffic channel that transmits user information. The MAC may have the function of multiplexing MAC SDUs belonging to one or more different logical channels and providing them to the PHY. The MAC may also have the function of demultiplexing MAC PDUs provided by the PHY and providing them to the higher layer via the logical channel to which each MAC SDU belongs. The MAC may also have the function of performing error correction through HARQ (Hybrid Automatic Repeat reQuest). The MAC may also have the function of reporting scheduling information. The MAC may have the function of performing priority processing between terminal devices using dynamic scheduling. The MAC may also have the function of performing priority processing between logical channels within a single terminal device. The MAC may have the function of performing priority processing of overlapping resources within a single terminal device. The E-UTRA MAC may have the function of identifying Multimedia Broadcast Multicast Services (MBMS). The NR MAC may also have the function of identifying Multicast/Broadcast Services (MBS). The MAC may have the function of selecting a transport format. The MAC may have functions such as discontinuous reception (DRX) and/or discontinuous transmission (DTX), a function to execute random access (RA) procedures, a power headroom report (PHR) function to notify information on the transmit power available, and a buffer status report (BSR) function to notify information on the amount of data in the transmit buffer. The NR MAC may have a bandwidth adaptation (BA) function. The MAC PDU format used in the E-UTRA MAC may differ from the MAC PDU format used in the NR MAC. The MAC PDU may also include a MAC control element (MAC CE), which is an element for performing control in the MAC.

The MAC sublayer may also provide additional services and functions on the PC5 interface, such as radio resource selection for selecting radio resources for sidelink transmission, filtering of packets received in sidelink communication, priority processing between uplink and sidelink, and reporting of sidelink channel state information (Sidelink CSI).

This article explains the sidelink (SL) logical channels used in E-UTRA and/or NR, and the mapping between the sidelink logical channels and transport channels.

The SBCCH (Sidelink Broadcast Control Channel) may be a logical channel for sidelink to broadcast sidelink system information from one terminal device to one or more terminal devices. The SBCCH may also be mapped to the SL-BCH, which is a sidelink transport channel.

The SCCH (Sidelink Control Channel) may be a sidelink logical channel for transmitting control information such as PC5-RRC messages and PC5-S messages from one terminal device to one or more terminal devices. The SCCH may also be mapped to the SL-SCH, which is a sidelink transport channel.

STCH (Sidelink Traffic Control Channel) may be a sidelink logical channel for transmitting user information from one terminal device to one or more terminal devices. STCH may also be mapped to SL-SCH, which is a sidelink transport channel.

An example of the RLC function is described below. RLC may be called an RLC sublayer. E-UTRA RLC may have the function of segmenting and/or concatenating data provided from the upper layer PDCP and providing it to the lower layer. E-UTRA RLC may have the function of reassembling and reordering data provided from the lower layer and providing it to the upper layer. NR RLC may have the function of adding a sequence number independent of the sequence number added by PDCP to data provided from the upper layer PDCP. NR RLC may also have the function of segmenting data provided from PDCP and providing it to the lower layer. NR RLC may also have the function of reassembling data provided from the lower layer and providing it to the upper layer. RLC may also have the function of retransmitting data and/or requesting retransmission (Automatic Repeat reQuest: ARQ). RLC may also have the function of performing error correction using ARQ. The control information sent from the receiving side of RLC to the transmitting side to perform ARQ, indicating the data that needs to be retransmitted, may be called a status report. The instruction to send a status report sent from the transmitting side of RLC to the receiving side may be called a poll. RLC may also have the function of detecting data duplication. RLC may also have the function of discarding data. RLC may have three modes: Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode (AM). In TM, data received from the upper layer is not divided, and an RLC header does not need to be added. The TM RLC entity is a uni-directional entity and may be configured as a transmitting TM RLC entity or a receiving TM RLC entity. In UM, the data received from the upper layer may be divided and/or combined, an RLC header may be added, etc., but data retransmission control is not required. The UM RLC entity may be a unidirectional entity or a bi-directional entity. If the UM RLC entity is a unidirectional entity, it may be configured as a transmitting UM RLC entity or a receiving UM RLC entity. If the UM RLC entity is a bi-directional entity, the UM RRC entity may be configured as a UM RLC entity consisting of a transmitting side and a receiving side. In AM, the data received from the upper layer may be divided and/or combined, an RLC header may be added, data retransmission control is required, etc. The AM RLC entity is a bi-directional entity and may be configured as an AM RLC consisting of a transmitting side and a receiving side. Note that data provided to the lower layer in TM and/or data provided from the lower layer may be called TMD PDU. Furthermore, data provided to a lower layer in UM and/or data provided by a lower layer may be referred to as a UMD PDU. Furthermore, data provided to a lower layer in AM and/or data provided by a lower layer may be referred to as an AMD PDU. The RLC PDU format used in E-UTRA RLC may differ from the RLC PDU format used in NR RLC. Furthermore, RLC PDUs may include RLC PDUs for data and RLC PDUs for control. The RLC PDUs for data may be referred to as RLC DATA PDU (RLC Data PDU, RLC Data PDU). The RLC PDUs for control may be referred to as RLC CONTROL PDU (RLC Control PDU, RLC Control PDU, RLC Control PDU). Furthermore, the RLC PDUs for control used to send status reports may be referred to as status PDU (STATUS PDU).

In addition, in the sidelink, TM may be used for SBCCH, only UM is used in groupcast and broadcast transmissions, and UM and AM can be used in unicast transmissions. Also, in the sidelink, UM in groupcast and broadcast transmissions supports only unidirectional transmission.

An example of the functions of PDCP is described below. PDCP may be called a PDCP sublayer. PDCP may have a function for maintaining sequence numbers. PDCP may also have a header compression/decompression function for efficiently transmitting user data such as IP packets and Ethernet frames over wireless sections. The protocol used for IP packet header compression/decompression may be called the ROHC (Robust Header Compression) protocol. The protocol used for Ethernet frame header compression/decompression may be called the EHC (Ethernet (registered trademark) Header Compression) protocol. PDCP may also have a data encryption/decryption function. PDCP may also have data integrity protection/verification functions. PDCP may also have a re-ordering function. PDCP may also have a PDCP SDU retransmission function. PDCP may also have a data discard function using a discard timer. PDCP may also have a duplication function. PDCP may also have the function of discarding duplicated data received. The PDCP entity is a bidirectional entity and may consist of a transmitting PDCP entity and a receiving PDCP entity. The PDCP PDU format used in E-UTRA PDCP may differ from the PDCP PDU format used in NR PDCP. PDCP PDUs may include data PDCP PDUs and control PDCP PDUs. The data PDCP PDU may be called PDCP DATA PDU (PDCP Data PDU, PDCP Data PDU). The control PDCP PDU may be called PDCP CONTROL PDU (PDCP Control PDU, PDCP Control PDU, PDCP Control PDU).

In addition, the following restrictions apply to PDCP functions and services in Sidelink:
(1) Out-of-order delivery may only be supported with unicast transmission.
(2) Duplication on the PC5 interface is not supported.

An example of the SDAP function is explained below. SDAP is a service data adaptation protocol layer. In the sidelink, SDAP may have a function of mapping the sidelink QoS flow sent from a terminal device to another terminal device with a sidelink data radio bearer (DRB). SDAP may also have a function of storing mapping rule information. SDAP may also have a function of marking the QoS flow identifier (QoS Flow ID: QFI). Note that SDAP PDUs may include data SDAP PDUs and control SDAP PDUs. Data SDAP PDUs may be called SDAP DATA PDUs (SDAP Data PDUs, SDAP Data PDUs). Control SDAP PDUs may be called SDAP CONTROL PDUs (SDAP Control PDUs, SDAP Control PDUs, SDAP Control PDUs). In addition, in the sidelink, the SDAP entity of the terminal device may exist for each destination for unicast transmission, groupcast transmission, or broadcast transmission associated with the destination. Also, reflective QoS is not supported on the PC5 interface.

An example of the functionality of RRC is described below. RRC may support services and functions such as forwarding PC5-RRC messages between peer UEs on the PC5 interface, maintaining and releasing PC5-RRC connections between two UEs, and detecting sidelink radio link failures for PC5-RRC connections. A PC5-RRC connection is a logical connection between two UEs corresponding to a pair of source L2ID and destination L2ID, and is considered to be established after the corresponding PC5 unicast link is established. There is also a one-to-one correspondence between the PC5-RRC connection and the PC5 unicast link. A UE may have multiple PC5-RRC connections to one or multiple UEs for different pairs of source L2ID and destination L2ID. Separate PC5-RRC procedures and messages may be used by the UE to forward UE capabilities and sidelink configuration to the peer UE. Both peer UEs may also exchange their UE capabilities and sidelink configurations with each other using separate bidirectional procedures. The UE releases the PC5-RRC connection if it is not interested in sidelink transmissions, if a sidelink radio link failure is detected for the PC5-RRC connection, and if the Layer 2 link release procedure is completed.

A UE performing sidelink transmission may transmit a PSCCH in association with a PSSCH. Note that sidelink transmission may be transmitting a signal and/or data (message) via a physical channel for sidelink (PSBCH, PSSCH, PSCCH, etc.), and sidelink reception may be receiving a signal and/or data (message) via a physical channel for sidelink. Also, communication using sidelink transmission and sidelink reception may be referred to as sidelink communication. The UE may recognize the data (message) based on the signal. Each PSSCH transmission may be associated with a PSCCH (a PSCCH) transmission. The PSCCH transmission may carry a first SCI (1st stage of the SCI) associated with the PSSCH transmission, and a second SCI (2nd stage of the SCI) may be carried within the resources of the PSSCH (the PSSCH). In addition, the PSCCH transmission may include a first SCI, and the PSSCH transmission may include a second SCI. Furthermore, the PSCCH transmission and the PSSCH transmission may be referred to as sidelink transmissions, and the SCI may be sidelink control information. The first SCI may include information in a format called SCI format 1-A, and may be used for scheduling the PSSCH and the second SCI on the PSSCH. SCI format 1-A may include information such as data priority, frequency resources and time resources on which the PSSCH is transmitted, resource reservation period, DMRS placement pattern, second SCI format, beta offset indication value, number of DMRS ports, information indicating modulation and coding scheme, and may include other information. Furthermore, the SCI carried on the PSSCH may be a second SCI, which may transport sidelink scheduling information and/or information related to inter-UE coordination. The second SCI may include information in a format called SCI format 2-A, SCI format 2-B, SCI format 2-C, etc. SCI format 2-A, SCI format 2-B, and SCI format 2-C may include information such as HARQ process related information, information indicating whether data is new, redundancy version, source ID for identifying a source UE, destination ID for identifying a destination UE, and information indicating whether HARQ feedback is possible. Furthermore, SCI format 2-A may additionally include information indicating a cast type and information indicating whether channel state information (CSI) is requested. Furthermore, SCI format 2-B may additionally include an identifier indicating a zone and request information regarding communication range. Furthermore, SCI format 2-C may additionally include information indicating whether to request channel state information, and information indicating whether to provide or request inter-UE coordination information. When SCI format 2-C includes information providing inter-UE coordination information, SCI format 2-C may additionally include information such as information indicating a resource combination, information indicating the first resource position, position information of the reference slot, information indicating the type of resource set, and lowest subchannel index. When SCI format 2-C includes information requesting inter-UE coordination information, SCI format 2-C may additionally include information such as priority, number of subchannels, resource reservation interval, position of the resource selection window, and information indicating the type of resource set. Note that each SCI format may include information other than the above-mentioned information.

Next, the procedure of the UE receiving the PSSCH will be described. When the UE detects SCI format 1-A on the PSCCH, it can decode the PSSCH according to the detected SCI format 2-A or SCI format 2-B and the associated PSSCH resource configuration configured by the higher layer. Note that the UE does not need to decode more than one PSCCH for each PSCCH resource candidate. Also, if the UE does not support the modulation and coding scheme indicated in SCI format 1-A, it does not need to decode the corresponding SCI format 2-A and SCI format 2-B, and the PSSCH associated with SCI format 1-A.

The UE may also measure the PSSCH RSRP from the DMRS resource element for the PSSCH associated with the received SCI format 1-A if PSSCH is set in the parameter indicating whether the DMRS used for L1 RSRP measurement during the sensing operation is the DMRS of the PSCCH or the DMRS of the PSSCH at the higher (RRC) layer, and may measure the PSCCH RSRP from the DMRS resource element for the PSCCH associated with the received SCI format 1-A if PSCCH is set.

A terminal device capable of sidelink communication may perform discovery. There may be Model A and Model B for discovery. Figure 4 shows the protocol stack for the discovery procedure. Mode A may use a single discovery protocol message, and Model B may use two discovery protocol messages. The single discovery protocol message in Model A may be an Announcement message, and the discovery protocol messages in Model B may be a Solicitation message and a Response message. The Announcement message, Solicitation message, and Response message may be collectively referred to as discovery messages, and messages with other names used in the discovery procedure may be referred to as discovery messages. Below is an overview of the Model A and Model B procedures in ProSe Direct Discovery.

In Model A, a UE that transmits an announcement message may be referred to as an Announcing UE, and a UE that monitors the announcement message may be referred to as a Monitoring UE. The announcement message may include information such as the type of discovery message, ProSe Application Code or ProSe Restricted Code, and security protection element, and may additionally include metadata information. The announcement message is transmitted using a Destination Layer-2 ID (L2ID) and a Source Layer-2 ID (L2ID), and the monitoring UE determines the destination L2ID to receive the announcement message. Note that the destination L2ID may be the Layer-2 identifier of the destination UE, and the source L2ID may be the Layer-2 identifier of the source UE. The destination UE may simply be referred to as the destination.

In Model B, a UE that sends a solicitation message may be referred to as a discoverer UE, and a UE that receives the solicitation message and/or sends a response message to the discoverer UE may be referred to as a discoveree UE. The solicitation message may include information such as a discovery message type, a ProSe Query Code, and a security protection element. The solicitation message is sent using a destination L2ID and a source L2ID, and the discoveree UE determines a destination L2ID to receive the solicitation message. The discoveree UE responding to the solicitation message also sends a response message. The response message may include information such as a discovery message type, a ProSe Response Code, and a security protection element, and may also include additional metadata information. The response message is sent using a source L2ID, and the destination L2ID is set to the source L2ID of the received solicitation message.

Discovery may include types other than ProSe Direct Discovery, which discovers other UEs in order to communicate directly with them, such as Group member Discovery, which discovers one or more UEs in order to communicate within a group using sidelink, and 5G ProSe UE-to-Network Relay Discovery, which discovers candidate relay UEs in order to connect to the network via a relay UE. Note that the above-mentioned discovery is an example of discovery provided by an application called ProSe, but in addition to the above-mentioned types, there may be different types of discovery depending on the application or service that performs sidelink communication. Also, the information included in the discovery protocol message may differ depending on the type of discovery, and additional messages may be sent to transmit additional information.

FIG. 4 is a diagram of an example of a protocol configuration including a discovery protocol according to this embodiment. As shown in FIG. 4, the protocol stack of the discovery plane including the discovery protocol may be composed of PHY (Physical layer) 200, which is a wireless physical layer, MAC (Medium Access Control) 202, which is a medium access control layer, RLC (Radio Link Control) 204, which is a radio link control layer, PDCP (Packet Data Convergence Protocol) 206, which is a packet data convergence protocol layer, and Discovery 400, which is a discovery protocol layer. Discovery 400 may be a protocol used to process procedures related to discovery. In addition, the interface between UEs performing discovery may be referred to as PC5-D.

Multiple resource pools may be configured for transmitting messages (discovery messages) used in discovery procedures, or one or more resource pools may be configured exclusively for discovery. If a resource pool dedicated to discovery is configured, the UE may use the resource pool dedicated to discovery as the resource pool for transmitting discovery messages, and if a resource pool dedicated to discovery is not configured, the UE may use the resource pool for sidelink communications as the resource pool for transmitting discovery messages. Note that multiple resource pools for sidelink communications and multiple resource pools dedicated to discovery may be configured at the same time. Each resource pool may be configured by UE-dedicated signaling, or may be configured in advance.

　In each unicast PC5-RRC connection, a sidelink signaling radio bearer (SRB) may be configured. A sidelink SRB used to transmit PC5-S messages before PC5-S security is established may be referred to as SL-SRB0. A sidelink SRB used to transmit PC5-S messages for establishing PC5-S security may be referred to as SL-SRB1. A sidelink SRB used to transmit protected PC5-S messages after PC5-S security is established may be referred to as SL-SRB2. A sidelink SRB used to transmit protected PC5-RRC signaling after PC5-S security is established may be referred to as SL-SRB3. A sidelink SRB used to transmit and/or receive discovery messages in NR may be referred to as SL-SRB4. PC5-RRC signaling may be RRC signaling between UEs transmitted and received on PC5. In addition, PC5-RRC signaling may be referred to as PC5-RRC message, etc.

Here, we will explain UE-to-Network (U2N) relay. U2N relay may be a function that provides network connectivity for remote terminal equipment (Remote UE). A remote terminal equipment that connects to a network using a U2N relay may be called a U2N Remote UE. Furthermore, a terminal equipment that provides network connectivity for a U2N Remote UE may be called a U2N relay terminal equipment (Relay UE), or simply a relay terminal equipment (Relay UE). A U2N Relay UE may use a Uu interface to communicate with a base station equipment, or may use a PC5 interface to communicate with a U2N Remote UE. Furthermore, there may be types of U2N relay, such as a Layer 2 (L2) U2N relay and a Layer 3 (L3) U2N relay. A remote terminal device in an L2 U2N relay may be specifically referred to as an L2 U2N Remote UE, and a relay terminal device in an L2 U2N relay may be specifically referred to as an L2 U2N Relay UE. In addition, a Sidelink Relay Adaptation Protocol (SRAP) layer may exist in an L2 U2N relay.

Figure 8 is a diagram showing an example of a protocol configuration of the control plane (C-plane) of an L2 U2N relay, including an SRAP layer (SRAP800) according to this embodiment. Also, Figure 9 is a diagram showing an example of a protocol configuration of the user plane (U-plane) of an L2 U2N relay, including an SRAP layer according to this embodiment. As shown in Figures 8 and 9, the SRAP layer may be associated between a Remote UE and a Relay UE, and may also be associated between a Relay UE and a gNB102. Note that the gNB102 shown in Figures 8 and 9 may be an ng-eNB100. Also, the Remote UE or Relay UE may be UE122. Also, the Relay UE may have the same configuration as UE122.

Here, we will explain the SRAP layer. The SRAP layer may be called the SRAP sublayer, or simply SRAP. The SRAP sublayer may exist above the RLC sublayer for the control plane and user plane of both the PC5 interface and the Uu interface. The SRAP sublayer on PC5 may be used for bearer mapping purposes. In an L2 U2N Relay UE, the SRAP sublayer may include one SRAP entity on the Uu interface and a separate collocated SRAP entity on the PC5 interface. In an L2 U2N Remote UE, the SRAP sublayer may include only one SRAP entity on the PC5 interface. The SRAP entity associated between the Remote UE and Relay UE via the PC5 interface may be specifically referred to as PC5-SRAP, and the SRAP entity associated between the Relay UE and gNB via Uu may be specifically referred to as Uu-SRAP. In addition, to clarify the interface name, other entities may also be expressed in the format (interface name)-(entity name) as in the case of SRAP. Each SRAP entity may have a transmitter and a receiver. On the PC5 interface, the transmitter of the SRAP entity of the L2 U2N Remote UE may be associated with the receiver of the SRAP entity of the L2 U2N Relay UE, and the receiver of the SRAP entity of the L2 U2N Remote UE may be associated with the transmitter of the SRAP entity of the L2 U2N Relay UE. Also, on the Uu interface, the transmitter of the SRAP entity of the L2 U2N Relay UE may be associated with the receiver of the SRAP entity of the gNB102, and the receiver of the SRAP entity of the L2 U2N Relay UE may be associated with the transmitter of the SRAP entity of the gNB102.

The SRAP entity may also have the functions of forwarding data, determining the UE ID field and bearer ID field of the SRAP header to be added to the data packet, determining the exit link, and determining the exit RLC channel.

Furthermore, in Figures 8 and 9, a PC5 Relay RLC channel may be established between the Remote UE and the Relay UE, and a Uu Relay RLC channel may be established between the Relay UE and gNB102.

Next, the protocol configuration used between the base station device and the terminal device will be described. The protocol used between the base station device and the terminal device may be used in the communication performed at the Uu interface between the relay terminal device and the base station device, and in the communication performed between the remote terminal device and the base station device via the relay terminal device. Note that in the communication performed between the remote terminal device and the base station device via the relay terminal device, some protocols may not be associated between the remote terminal device and the base station device.

FIG. 7 is a diagram of an example of the NR protocol configuration according to this embodiment. The functions of each protocol described using FIG. 7 are some of the functions closely related to this embodiment, and may have other functions. Note that in this embodiment, the uplink (UL) may be a link from the terminal device to the base station device. Also, in this embodiment, the downlink (DL) may be a link from the base station device to the terminal device.

Figure 7(A) is a diagram of the NR control plane (CP) protocol stack. As shown in Figure 7(A), the NR CP protocol may be a protocol between the UE 122 and the gNB 102. That is, the NR CP protocol may be a protocol that terminates at the gNB 102 on the network side. As shown in Figure 7(A), the NR control plane protocol stack may be composed of PHY (Physical layer) 700, which is the radio physical layer, MAC (Medium Access Control) 702, which is the medium access control layer, RLC 704, which is the radio link control layer, PDCP (Packet Data Convergence Protocol) 706, which is the packet data convergence protocol layer, and RRC (Radio Resource Control) 708, which is the radio resource control layer. Also, Figure 7(B) is a diagram of the NR user plane (UP) protocol stack. As shown in FIG. 7(B), the NR UP protocol may be a protocol between the UE 122 and the gNB 102. That is, the NR UP protocol may be a protocol that terminates at the gNB 102 on the network side. As shown in FIG. 7(B), the NR user plane protocol stack may be composed of a radio physical layer, PHY 700, a medium access control layer, MAC 702, a radio link control layer, RLC 704, a packet data convergence protocol layer, PDCP 706, and a service data adaptation protocol layer, SDAP (Service Data Adaptation Protocol) 710.

The AS (Access Stratum) layer may be a layer that terminates between the UE 122 and the gNB 102. In other words, the AS layer may be a layer that includes some or all of the PHY 700, MAC 702, RLC 704, PDCP 706, and RRC 708. The gNB 102 may be an ng-eNB 100. Although only the NR protocol is shown, the E-UTRA protocol may also be used. In the E-UTRA protocol, the SDAP 710 may not exist, and the E-UTRA protocol may have some functions that differ from those of the NR protocol.

An example of the functions of the PHY will be described. The PHY of the terminal device may have a function of receiving data transmitted from the PHY of the base station device via a downlink (DL) physical channel. The PHY of the terminal device may have a function of transmitting data to the PHY of the base station device via an uplink (UL) physical channel. The PHY may be connected to an upper MAC via a transport channel. The PHY may pass data to the MAC via the transport channel. The PHY may also be provided with data from the MAC via the transport channel. In the PHY, a Radio Network Temporary Identifier (RNTI) may be used to identify various control information.

Here, we will explain physical channels. The physical channels used for wireless communication between a terminal device and a base station device may include the following physical channels:

PBCH (Physical Broadcast CHannel)
PDCCH (Physical Downlink Control CHannel)
PDSCH (Physical Downlink Shared CHannel)
PUCCH (Physical Uplink Control CHannel)
PUSCH (Physical Uplink Shared CHannel)
PRACH (Physical Random Access CHannel)

The PBCH may be used to notify the terminal device of system information required.

In addition, in NR, the PBCH may be used to report the time index (SSB-Index) within the period of a synchronization signal block (SSB).

The PDCCH may be used to transmit (or carry) downlink control information (DCI) in downlink wireless communication (wireless communication from a base station device to a terminal device). Here, one or more DCIs (which may also be referred to as DCI formats) may be defined for the transmission of the downlink control information. That is, a field for the downlink control information may be defined as a DCI and mapped to information bits. The PDCCH may be transmitted in PDCCH candidates. The terminal device may monitor a set of PDCCH candidates in a serving cell. Monitoring a set of PDCCH candidates may mean attempting to decode the PDCCH according to a certain DCI format. In addition, the terminal device may monitor the PDCCH candidates in configured monitoring occasions in one or more configured control resource sets (CORESET: Control Resource Set) configured by search space configuration. The DCI format may be used for scheduling the PUSCH in the serving cell. The PUSCH may be used to transmit user data and RRC messages, which are described below.

PDCCH repetition may be operated by using two search space sets that are explicitly linked by a configuration provided by a higher layer (RRC layer), and the two linked search space sets may be associated with a corresponding CORESET. For PDCCH repetition, the two linked search space sets may be configured in the terminal device with the same number of PDCCH candidates. The two PDCCH candidates present in the two linked search space sets may be linked by the same candidate index. When PDCCH repetition is scheduled in the terminal device, inter-slot repetition may be allowed, and each repetition may have the same number of Control Channel Elements (CCEs) and coded bits, and the same DCI payload.

The PUCCH may be used to transmit uplink control information (UCI) in uplink wireless communication (wireless communication from a terminal device to a base station device). Here, the uplink control information may include channel state information (CSI: Channel State Information) used to indicate the state of the downlink channel. The uplink control information may also include a scheduling request (SR: Scheduling Request) used to request UL-SCH (UL-SCH: Uplink Shared CHannel) resources. The uplink control information may also include a HARQ-ACK (Hybrid Automatic Repeat reQuest ACKnowledgement).

The PDSCH may be used to transmit downlink data (DL-SCH: Downlink Shared CHannel) from the MAC layer. In the case of the downlink, the PDSCH may also be used to transmit system information (SI: System Information) and random access response (RAR: Random Access Response).

PUSCH may be used to transmit uplink data from the MAC layer (UL-SCH: Uplink Shared CHannel) or HARQ-ACK and/or CSI together with uplink data. PUSCH may also be used to transmit only CSI, or only HARQ-ACK and CSI. That is, PUSCH may be used to transmit only UCI. PDSCH or PUSCH may also be used to transmit RRC messages and MAC CE, which will be described later. Here, in the PDSCH, the RRC message transmitted from the base station device may be common signaling for multiple terminal devices in the cell. The RRC message transmitted from the base station device may also be dedicated signaling for a certain terminal device. That is, terminal device-specific (UE specific) information may be transmitted using dedicated signaling for a certain terminal device. PUSCH may also be used to transmit UE capabilities in the uplink.

The PRACH may be used to transmit a random access preamble. The PRACH may also be used for initial connection establishment procedures, handover procedures, connection re-establishment procedures, synchronization (timing adjustment) for uplink transmissions, and to indicate requests for UL-SCH resources.

This article explains the logical channels for the uplink (UL) and/or downlink (DL) used in E-UTRA and/or NR.

The BCCH (Broadcast Control Channel) may be a downlink logical channel for broadcasting control information such as system information (SI).

PCCH (Paging Control Channel) may be a downlink logical channel for carrying paging messages.

The Common Control Channel (CCCH) may be a logical channel for transmitting control information between a terminal device and a base station device. The CCCH may be used when the terminal device does not have an RRC connection. The CCCH may also be used between a base station device and multiple terminal devices.

　DCCH (Dedicated Control Channel) may be a logical channel for transmitting dedicated control information in a point-to-point bidirectional manner between a terminal device and a base station device. The dedicated control information may be control information dedicated to each terminal device. DCCH may be used when the terminal device has an RRC connection.

DTCH (Dedicated Traffic Channel) may be a logical channel for transmitting user data point-to-point between a terminal device and a base station device. DTCH may be a logical channel for transmitting dedicated user data. Dedicated user data may be user data dedicated to each terminal device. DTCH may exist in both the uplink and downlink.

Describes the mapping of logical channels and transport channels for the uplink in E-UTRA and/or NR.

The CCCH may be mapped to the uplink transport channel, UL-SCH (Uplink Shared Channel).

The DCCH may be mapped to the uplink transport channel, UL-SCH (Uplink Shared Channel).

The DTCH may be mapped to the uplink transport channel, UL-SCH (Uplink Shared Channel).

Describes the mapping of logical channels and transport channels for the downlink in E-UTRA and/or NR.

The BCCH may be mapped to the downlink transport channels BCH (Broadcast Channel) and/or DL-SCH (Downlink Shared Channel).

The PCCH may be mapped to the PCH (Paging Channel), which is a downlink transport channel.

The CCCH may be mapped to the downlink transport channel, DL-SCH (Downlink Shared Channel).

The DCCH may be mapped to the downlink transport channel, DL-SCH (Downlink Shared Channel).

DTCH may be mapped to the downlink transport channel, DL-SCH (Downlink Shared Channel).

An example of the SDAP function is described below. SDAP is a service data adaptation protocol layer. SDAP may have a function to map the downlink QoS flow sent from 5GC to the terminal device via the base station device with the data radio bearer (DRB), and/or map the uplink QoS flow sent from the terminal device to 5GC via the base station device with the DRB. SDAP may also have a function to store mapping rule information. SDAP may also have a function to mark the QoS flow identifier (QoS Flow ID: QFI). Note that there may be an SDAP PDU for data and an SDAP PDU for control. The SDAP PDU for data may be called the SDAP DATA PDU (SDAP Data PDU, SDAP Data PDU). The SDAP PDU for control may be called the SDAP CONTROL PDU (SDAP Control PDU, SDAP Control PDU, SDAP Control PDU). There may be one SDAP entity in a terminal device per PDU session.

An example of the RRC functions will be described. RRC may have a broadcast function. RRC may have a paging function from 5GC. RRC may have a paging function from gNB102 or ng-eNB100. RRC may also have an RRC connection management function. RRC may have a radio bearer control function. RRC may have a cell group control function. RRC may also have a mobility control function. RRC may also have terminal device measurement reporting and terminal device measurement reporting control functions. RRC may also have a QoS management function. RRC may also have a radio link failure detection and recovery function. RRC may use RRC messages to perform broadcasting, paging, RRC connection management, radio bearer control, cell group control, mobility control, terminal device measurement reporting and terminal device measurement reporting control, QoS management, radio link failure detection and recovery, etc. Note that the RRC messages and parameters used in E-UTRA RRC may differ from the RRC messages and parameters used in NR RRC.

The RRC messages may be sent using the logical channel BCCH, the logical channel PCCH, the logical channel CCCH, or the logical channel DCCH. RRC messages sent using the DCCH are called Dedicated RRC signaling, or RRC signaling.

RRC messages sent using the BCCH may include, for example, a Master Information Block (MIB), various types of System Information Blocks (SIBs), and other RRC messages. RRC messages sent using the PCCH may include, for example, paging messages, and other RRC messages.

RRC messages sent in the uplink (UL) direction using the CCCH may include, for example, an RRC setup request message (RRC Setup Request), an RRC resume request message (RRC Resume Request), an RRC reestablishment request message (RRC Reestablishment Request), an RRC system information request message (RRC System Info Request), etc. They may also include, for example, an RRC connection request message (RRC Connection Request), an RRC connection resume request message (RRC Connection Resume Request), an RRC connection reestablishment request message (RRC Connection Reestablishment Request), etc. They may also include other RRC messages.

RRC messages sent in the downlink (DL) direction using the CCCH may include, for example, an RRC connection reject message (RRC Connection Reject), an RRC connection setup message (RRC Connection Setup), an RRC connection reestablishment message (RRC Connection Reestablishment Reject), an RRC connection reestablishment reject message (RRC Connection Reestablishment Reject), etc. They may also include, for example, an RRC reject message (RRC Reject), an RRC setup message (RRC Setup), etc. They may also include other RRC messages.

RRC signalling sent in the uplink (UL) direction using the DCCH may include, for example, a measurement report message (Measurement Report), an RRC connection reconfiguration complete message (RRC Connection Reconfiguration Complete), an RRC connection setup complete message (RRC Connection Setup Complete), an RRC connection reestablishment complete message (RRC Connection Reestablishment Complete), a security mode complete message (Security Mode Complete), and a UE capability information message (UE Capability Information). It may also include, for example, a measurement report message (Measurement Report), an RRC reconfiguration complete message (RRC Reconfiguration Complete), an RRC setup complete message (RRC Setup Complete), an RRC reestablishment complete message (RRC Resumé Complete), a security mode complete message (Security Mode Complete), a UE capability information message (UE Capability Information), etc. It may also include other RRC signaling.

The RRC signaling sent in the downlink (DL) direction using the DCCH may include, for example, an RRC connection reconfiguration message (RRC Connection Reconfiguration), an RRC connection release message (RRC Connection Release), a security mode command message (Security Mode Command), a UE capability enquiry message (UE Capability Enquiry), etc. It may also include, for example, an RRC reconfiguration message (RRC Reconfiguration), an RRC resume message (RRC Resume), an RRC release message (RRC Release), an RRC reestablishment message (RRC Reestablishment), a security mode command message (Security Mode Command), a UE capability enquiry message (UE Capability Enquiry), etc. It may also include other RRC signaling.

The above-mentioned PHY, MAC, RLC, PDCP, SDAP, and RRC functions are just examples, and some or all of the functions may not be implemented. In addition, some or all of the functions of each layer may be included in other layers.

　Explains radio bearers. When a terminal device communicates with a base station device, a wireless connection may be established by establishing a radio bearer (RB: Radio Bearer) between the terminal device and the base station device. The radio bearer used for CP may be called a signaling radio bearer (SRB: Signaling Radio Bearer). The radio bearer used for UP may be called a data radio bearer (DRB: Data Radio Bearer). Each radio bearer may be assigned a radio bearer identifier (Identity: ID). The radio bearer identifier for an SRB may be called an SRB identifier (SRB Identity, or SRB ID). The radio bearer identifier for a DRB may be called a DRB identifier (DRB Identity, or DRB ID). SRB0 to SRB2 may be defined for the SRB of E-UTRA, and other SRBs may also be defined. NR SRBs may be defined as SRB0 to SRB3, or other SRBs may be defined. SRB0 may be an SRB for RRC messages, which are transmitted and/or received using the logical channel CCCH. SRB1 may be an SRB for RRC signaling and for NAS signaling before establishment of SRB2. The RRC signaling transmitted and/or received using SRB1 may include piggybacked NAS signaling. The logical channel DCCH may be used for all RRC and NAS signaling transmitted and/or received using SRB1. SRB2 may be an SRB for NAS signaling and for RRC signaling including logged measurement information. The logical channel DCCH may be used for all RRC and NAS signaling transmitted and/or received using SRB2. Also, SRB2 may have a lower priority than SRB1. SRB3 may be an SRB for transmitting and/or receiving specific RRC signaling when EN-DC, NGEN-DC, NR-DC, etc. are configured in the terminal device. The logical channel DCCH may be used for all RRC signaling and NAS signaling transmitted and/or received using SRB3. Other SRBs may also be provided for other uses. The DRB may be a radio bearer for user data. The logical channel DTCH may be used for RRC signaling transmitted and/or received using the DRB.

The following describes the radio bearer in the terminal device. The radio bearer may include an RLC bearer. The RLC bearer may be composed of one or two RLC entities and logical channels. When there are two RLC entities in an RLC bearer, the RLC entities may be a TM RLC entity, and/or a transmitting RLC entity and a receiving RLC entity in a unidirectional UM mode RLC entity. SRB0 may be composed of one RLC bearer. The RLC bearer of SRB0 may be composed of a TM RLC entity and a logical channel. SRB0 may always be established in the terminal device in all states (RRC idle state, RRC connected state, RRC inactive state, etc.). SRB1 may be established and/or configured in the terminal device by RRC signaling received from the base station device when the terminal device transitions from the RRC idle state to the RRC connected state. SRB1 may be composed of one PDCP entity and one or more RLC bearers. The RLC bearer of SRB1 may be composed of an AM RLC entity and a logical channel. SRB2 may be established and/or configured in the terminal device by RRC signaling received from the base station device by the terminal device in the RRC connected state with AS security activated. SRB2 may be composed of one PDCP entity and one or more RLC bearers. The RLC bearer of SRB2 may be composed of an RLC entity of AM and a logical channel. The PDCP of SRB1 and SRB2 on the base station device side may be placed in the master node. SRB3 may be established and/or configured in the terminal device by RRC signaling received from the base station device by the terminal device in the RRC connected state with AS security activated when a secondary node is added in EN-DC, NGEN-DC, or NR-DC, or when the secondary node is changed. SRB3 may be a direct SRB between the terminal device and the secondary node. SRB3 may be composed of one PDCP entity and one or more RLC bearers. The RLC bearer of SRB3 may be composed of an RLC entity of AM and a logical channel. The PDCP on the base station side of SRB3 may be placed in a secondary node. One or more DRBs may be established and/or configured in a terminal device by RRC signaling received from a base station device by a terminal device in an RRC connected state with AS security activated. A DRB may consist of one PDCP entity and one or more RLC bearers. The RLC bearer of the DRB may consist of an AM or UM RLC entity and a logical channel.

For an RLC bearer established and/or configured in a cell group consisting of E-UTRA, the RLC entity established and/or configured may be an E-UTRA RLC. For an RLC bearer established and/or configured in a cell group consisting of NR, the RLC entity established and/or configured may be an NR RLC. When an EN-DC is configured in the terminal device, the PDCP entity established and/or configured for the Master Node terminated MCG bearer may be either an E-UTRA PDCP or an NR PDCP. When an EN-DC is configured in the terminal device, the PDCP entity established and/or configured for the radio bearers of other bearer types, i.e., Master Node terminated split bearer, Master Node terminated SCG bearer, Secondary Node terminated MCG bearer, Secondary Node terminated split bearer, and Secondary Node terminated SCG bearer, may be an NR PDCP. Also, when NGEN-DC, NE-DC, or NR-DC is configured in the terminal device, the PDCP entity established and/or configured for radio bearers in all bearer types may be an NR PDCP.

In addition, in NR, a DRB established and/or configured in a terminal device may be linked to one PDU session. One SDAP entity may be established and/or configured for one PDU session in the terminal device. The SDAP entity, PDCP entity, RLC entity, and logical channels established and/or configured in the terminal device may be established and/or configured by RRC signaling received by the terminal device from the base station device.

The operations of RRC, PDCP and RLC closely related to this embodiment will be described. First, PDCP data recovery and PDCP re-establishment will be described. RRC signaling transmitted from a base station device to a terminal device may include an information element (RadioBearerConfig) regarding the configuration of a radio bearer, and the information element regarding the configuration of a radio bearer may include a list (DRB-ToAddModList) of settings (DRB-ToAddMod) regarding the addition and/or modification of a DRB, and the settings regarding the addition and/or modification of a DRB may include a DRB identifier (drb-Identity), information indicating that PDCP is to be re-established (reestablishPDCP), and information indicating that PDCP is to perform data recovery (recoverPDCP). The RRC of the terminal device may re-establish a PDCP entity of a DRB identified by a DRB identifier based on information indicating that PDCP is re-established being set in the RRC signaling, and may trigger data recovery of a PDCP entity set in a DRB identified by a DRB identifier based on information indicating that PDCP is to perform data recovery being set in the RRC signaling. If information indicating that PDCP is re-established and information indicating that PDCP is to perform data recovery are included in the configuration for adding and/or modifying a DRB identified by one DRB identifier, the RRC of the terminal device may re-establish a PDCP entity of a DRB identified by the DRB identifier, and may not trigger data recovery of a PDCP entity of a DRB identified by the DRB identifier.

A PDCP entity that has been requested to recover data by upper layers (RRC layer) may retransmit all PDCP data PDUs that have not been confirmed as successfully delivered by lower layers and that have been previously submitted to the re-established or released AM RLC entity in ascending order of the COUNT values associated with the PDUs.

A PDCP entity that is requested by a higher layer (RRC layer) to re-establish a PDCP entity may retransmit or transmit all PDCP SDUs already associated with PDCP sequence numbers (Sequence Number(s): SN(s)) in ascending order of the COUNT values associated with the PDCP SDUs before the PDCP re-establishment, starting from the first PDCP SDU for which successful delivery of the corresponding PDCP data PDU has not been confirmed by the lower layer. If the DRB containing the PDCP entity that is requested to be re-established is suspended, the PDCP entity may consider the PDCP SDU to have been received from the higher layer and may retransmit the PDCP SDU without restarting the discard timer.

A PDCP entity may consist of a transmitting PDCP entity and a receiving PDCP entity. Upon receiving a PDCP SDU from an upper layer, the transmitting PDCP entity may start a discard timer associated with that PDCP SDU. If the discard timer for that PDCP SDU expires or if successful delivery of the PDCP SDU is confirmed by a PDCP status report, the transmitting PDCP entity may discard the PDCP SDU together with the corresponding PDCP data PDU. If the PDCP data PDU has already been submitted to the lower layer, the lower layer may be instructed to discard.

For an AM DRB configured to send a PDCP status report to the upper layer (RRC) on the uplink, the receiving PDCP entity may trigger a PDCP status report when the upper layer (RRC) requests re-establishment of the PDCP entity, when the upper layer (RRC) requests PDCP data recovery, when the upper layer (RRC) requests a switch of uplink data, etc. The RRC of the terminal device may configure the DRB identified by the DRB identifier to send a PDCP status report on the uplink based on the fact that the PDCP entity configuration (pdcp-Config) included in the configuration for adding and/or modifying a DRB includes information (statusReportRequired) indicating that a PDCP status report is to be sent on the uplink. When a PDCP status report is triggered, the receiving PDCP entity may submit the PDCP status report to the lower layer as the first PDCP PDU for transmission via the transmitting PDCP entity.

The control PDCP PDU may be used to transmit a PDCP status report to the peer PDCP. In addition, the control PDCP PDU may also be used to transmit control information other than the PDCP status report. The PDCP status report may include information indicating whether the PDCP PDU is for control or data, information indicating which control information is included among the control information that can be included in the control PDCP PDU, reserved bits, information indicating the first PDCP PDU that is missing within the reordering window (First Missing COUNT: FMC), and bitmap information indicating the missing PDCP SDUs and the successfully received PDCP SDUs.

When a PDCP status report is received on the downlink, the transmitting PDCP entity may consider as successfully delivered PDCP SDUs corresponding to COUNT values corresponding to bits indicated as 1 in the bitmap information contained in the PDCP status report and/or COUNT values smaller than the value indicated by the FMC, and may discard PDCP SDUs considered as successfully delivered.

The transmitting AM RLC entity may receive a positive ACKnowledgement (ACK) for an RLC SDU via a status PDU from the peer AM RLC entity. When an ACK for an RLC SDU associated with an RLC sequence number is received, the transmitting AM RLC entity may notify the upper layer of successful delivery of said RLC SDU. Also, when an instruction to discard a particular RLC SDU is received from the upper layer (PDCP), the transmitting AM RLC entity may discard the indicated RLC SDU if the indicated RLC SDU or a segment of it has not been submitted to the lower layer.

Reference signal received power (RSRP) measured in the sidelink may be, for example, the following RSRP. In addition, the following RSRP may be referred to as SL-RSRP.
(a) PSBCH RSRP
(b) PSSCH RSRP
(c) PSCCH RSRP

The PSBCH-RSRP (PSBCH RSRP) may be defined as the linear average of the power contributions of resource elements transmitting multiple Demodulation Reference Signals (DMRSs) associated with the PSBCH. The PSSCH-RSRP (PSSCH RSRP) may be defined as the linear average of the power contributions of resource elements of antenna ports transmitting multiple DMRSs associated with the PSSCH, and in the case of multiple antenna ports, the RSRP values for each antenna port may be summed. The PSCCH-RSRP (PSCCH RSRP) may be defined as the linear average of the power contributions of resource elements transmitting multiple DMRSs associated with the PSCCH. The DMRSs may be used, for example, to demodulate the PSBCH, PSSCH and PSCCH signals. Furthermore, a terminal device that performs sidelink communication with another terminal device may measure the RSRP of the sidelink communication (SL-RSRP) using the PSSCH or PSCCH transmitted from the other terminal device. Furthermore, the terminal device may measure the RSRP of the discovery message (SD-RSRP) using the power contribution of the resource element that transmits the DMRS associated with the discovery message.

In addition, in measurements on the sidelink, UE 122 may measure the following quantities in addition to SL-RSRP:
(a) Sidelink received signal strength indicator (SL RSSI)
(b) Sidelink channel Occupancy ratio (SL CR)
(c) Sidelink channel busy ratio(SL CBR)

The SL RSSI may be defined as the linear average of the power ([W]) observed on the configured subchannels in the OFDM symbols of the slots configured for PSCCH and PSSCH starting from the second OFDM symbol. The SL CR in slot n may be defined as the sum of the number of subchannels used for sidelink transmission from slot [n-a] to slot [n-1] and the number of subchannels allocated from slot [n] to slot [n+b] divided by the total number of subchannels configured from slot [n-a] to slot [n+b]. The SL CBR in slot n may be defined as the percentage of subchannels in the resource pool whose SL RSSI exceeds a threshold during the period configured as the CBR measurement window (slot [n-a] to slot [n-1]).

After discovering candidate L2 U2N Relay UEs and measuring the RSRP of the candidate L2 U2N Relay UEs, the L2 U2N Remote UE may report one or more candidate L2 U2N Relay UEs to the base station device. Note that before reporting one or more candidate L2 U2N Relay UEs to the base station device, the L2 U2N Remote UE may determine whether the measured RSRP of the candidate L2 U2N Relay UEs satisfies the L2 U2N relay selection criteria. The L2 U2N Remote UE may report only candidate L2 U2N Relay UEs that satisfy the selection criteria and match the upper layer criteria to the base station device. In addition, when the L2 U2N Remote UE reports one or more candidate L2 U2N Relay UEs to the base station device, the report to the base station device may include identification information of the candidate L2 U2N Relay UEs, identification information of the serving cell of the candidate L2 U2N Relay UEs, and measurement results. Note that the measurement results may use the RSRP (SD-RSRP) of the discovery message transmitted by the candidate L2 U2N Relay UEs. Note that the identification information may be an identifier (ID).

Furthermore, an L2 U2N Remote UE having a serving L2 U2N Relay UE may use RSRP (SL-RSRP) measured in sidelink communication with the serving L2 U2N Relay UE as the measurement result. Note that if SL-RSRP cannot be used as the measurement result, SD-RSRP may be used. Note that the serving L2 U2N Relay UE may be an L2 U2N Relay UE that provides connectivity to a base station device for the L2 U2N Remote UE.

Next, the serving cell will be described. In a terminal device in an RRC connected state where carrier aggregation (CA) and/or multi-connectivity (MC) is not configured, the serving cell may be composed of one primary cell (Primary Cell: PCell). In addition, in a terminal device in an RRC connected state where CA and/or MC are configured, multiple serving cells may refer to a set of multiple cells (set of cell(s)) composed of one or more special cells (Special Cell: SpCell) and one or more all secondary cells (Secondary Cell: SCell). The SpCell may support PUCCH transmission and contention-based random access (CBRA). The PCell may be a cell used in the RRC connection establishment procedure when a terminal device in an RRC idle state transitions to an RRC connected state. The PCell may also be a cell used in the RRC connection re-establishment procedure in which the terminal device re-establishes the RRC connection. The PCell may also be a cell used for a random access procedure during handover. The PSCell may also be a cell used for a random access procedure when adding a secondary node for MC. The PCell and PSCell may also be SpCells. The SpCell may also be a cell used for purposes other than those mentioned above.

Based on the above explanation, various embodiments of the present invention will be described. Note that the above-mentioned processes may be applied to the processes omitted in the following explanation.

FIG. 5 is a block diagram showing the configuration of a terminal device (UE122) in this embodiment. Note that, to avoid complicating the explanation, FIG. 5 shows only the main components closely related to this embodiment.

The UE122 shown in FIG. 5 includes a receiver 500 that receives control information (SCI, MAC control element, RRC signaling, etc.), discovery messages, information including user data, etc. from other terminal devices, a processor 502 that performs processing according to parameters included in the received control information, etc., and a transmitter 504 that transmits control information (SCI, MAC control element, RRC signaling, etc.), discovery messages, information including user data, etc. to other terminal devices. The receiver 500 may also receive control information (MAC control element, RRC signaling, etc.) and information including user data, etc. from a base station device (gNB102). The transmitter 504 may also transmit control information (MAC control element, RRC signaling, etc.) and information including user data, etc. to the base station device (gNB102). Furthermore, the processing unit 502 may include some or all of the functions of various layers (e.g., the physical layer, MAC layer, RLC layer, PDCP layer, SDAP layer, RRC layer, PC5-S layer, Discovery layer, and application layer). That is, the processing unit 502 may include some or all of the physical layer processing unit (PHY processing unit), MAC layer processing unit (MAC processing unit), RLC layer processing unit (RLC processing unit), PDCP layer processing unit (PDCP processing unit), SDAP processing unit (SDAP processing unit), RRC layer processing unit (RRC processing unit), PC5-S layer processing unit (PC5-S processing unit), Discovery layer processing unit (Discovery processing unit), and application layer processing unit.

FIG. 6 is a block diagram showing the configuration of a base station device (gNB102) in this embodiment. Note that to avoid complicating the explanation, FIG. 6 shows only the main components closely related to this embodiment.

The base station device shown in FIG. 6 comprises a transmitter 604 that transmits control information (DCI, MAC CE, RRC signaling, etc.) to UE 122, a processor 602 that creates control information (DCI, MAC CE, RRC signaling, etc.) and transmits it to UE 122, thereby causing the processor 502 of UE 122 to process it, and a receiver 600 that receives control information (UCI, MAC CE, RRC signaling, etc.) from UE 122. The processor 602 may include some or all of the functions of various layers (e.g., physical layer, MAC layer, RLC layer, PDCP layer, SDAP layer, RRC layer, and NAS layer). That is, the processor 602 may include some or all of the physical layer processor, MAC layer processor, RLC layer processor, PDCP layer processor, SDAP processor, RRC layer processor, and NAS layer processor.

Figure 10 shows an example of an embodiment of one aspect of the present invention.

UE 122, which communicates with the base station device, judges the information (step S1000) and performs an action based on the judgment (step S1002).

The RRC layer of the UE that has received the first RRC signaling and the second RRC signaling from the base station device may instruct the lower layer (PDCP layer) based on the first RRC signaling and the second RRC signaling. In step S1000, the information may be, for example, the instruction. The PDCP layer that has received the information from the upper layer (RRC layer) may determine, for example, whether the information includes first information in step S1000. If the PDCP layer of the UE 122 determines that the information includes the first information, it may perform a first operation, for example, in step S1002, and if it determines that the information does not include the first information, it may perform a second operation, for example, in step S1002. The first information may be information indicating that the device is a remote terminal device, or may be information indicating that the first operation is to be performed. The first RRC signaling may also be an RRC message including settings for a remote terminal device, or may be an RRC message including information indicating that the first operation is to be performed. The second RRC signaling may be an RRC message including information indicating that PDCP data recovery is to be performed, or may be an RRC message including information indicating that PDCP re-establishment is to be performed.

The RRC layer of the UE 122 may determine whether or not to perform the first setting based on the first RRC signaling. For example, the first setting may be performed based on the first RRC signaling including a setting for a remote terminal device, or the first setting may not be performed based on the first RRC signaling not including a setting for a remote terminal device. For example, the first setting may be performed based on the first RRC signaling including information indicating that the first operation is to be performed, or the first setting may not be performed based on the first RRC signaling not including information indicating that the first operation is to be performed. The RRC layer of the UE 122 may also determine whether or not to provide the first information to a lower layer based on whether or not the first setting is performed. For example, the RRC layer of the UE 122 may determine to provide the first information to a lower layer based on the first setting being performed, or may determine not to provide the first information to a lower layer based on the first setting not being performed. The first RRC signaling and the second RRC signaling may be one RRC signaling. For example, the RRC signaling may include information indicating that the first operation is to be performed and information indicating that PDCP data recovery is to be performed, or may include information indicating that the first operation is to be performed and information indicating that PDCP re-establishment is to be performed, or may be another combination.

The RRC layer of the UE 122 may also determine the information based on the second RRC signaling. If the second signaling includes information indicating that PDCP data recovery is to be performed, the RRC layer may determine to instruct a lower layer to perform PDCP data recovery, and if the second signaling includes information indicating that PDCP re-establishment is to be performed, the RRC layer may determine to instruct a lower layer to perform PDCP re-establishment. Note that instructing a lower layer may be said as providing information to a lower layer.

The first action may be, if the information includes information instructing to perform PDCP data recovery, a retransmission of all PDCP data PDUs previously submitted to the re-established or released AM RLC entity. All the PDCP data PDUs may be referred to as all PDCP data PDUs that have not been discarded. The first action may also be, if the information includes information instructing to perform PDCP re-establishment, a retransmission or transmission of all PDCP SDUs already associated with a PDCP SN, starting from the first PDCP SDU, in ascending order of the COUNT values associated with the PDCP SDUs before the re-establishment of the PDCP entity. All the PDCP SDUs may be referred to as all PDCP SDUs that have not been discarded. The second action may be, if the information includes information instructing to perform PDCP data recovery, a retransmission of all PDCP data PDUs previously submitted to the re-established or released AM RLC entity, for which successful transmission of the corresponding PDCP data PDUs has not been confirmed by a lower layer, starting from the first PDCP SDU. Furthermore, if the information includes information instructing to perform PDCP re-establishment, the second action may be to retransmit or transmit, starting from the first PDCP SDU, all PDCP SDUs already associated with a PDCP SN and for which successful transmission of the corresponding PDCP data PDU has not been confirmed by a lower layer, in ascending order of the COUNT values associated with the PDCP SDUs before the re-establishment of the PDCP entity. Note that the term "successful transmission" may be interchangeable with the term "successful delivery."

The UE 122 may communicate with the base station device via a relay terminal device. In other words, the UE 122 may be a terminal device playing the role of a remote UE. If the first RRC signaling includes a setting for a remote terminal device, the second RRC signaling includes information indicating that PDCP data recovery is to be performed or information indicating that PDCP re-establishment is to be performed, the first RRC signaling and the second RRC signaling are one RRC signaling, and the terminal device is not playing the role of a remote UE immediately before receiving the RRC signaling, the first operation may not be performed. In other words, if the terminal device receives the second RRC signaling including information indicating that PDCP data recovery is to be performed or information indicating that PDCP re-establishment is to be performed when not playing the role of a remote UE, the terminal device may not perform the first operation. In addition, the settings for the remote terminal device may be, for example, settings related to the U2N relay used by the remote terminal device that are included in the RRC message, and the settings related to the U2N relay used by the remote terminal device may include settings of the SRAP layer used by the remote terminal device.

Furthermore, Figure 10 shows an example of another embodiment of one aspect of the present invention.

UE122, which communicates with the base station device and the remote terminal device, judges the information (step S1000) and performs an action based on the judgment (step S1002).

In step S1000, the determination may be, for example, determining whether or not first information has been received from a base station device. In step S1002, if UE 122 determines in the determination that it has received the first information, the operation may be, for example, performing a first operation, or if UE 122 determines in the determination that it has not received the first information, the operation may be, for example, not performing the first operation. The first information may be, for example, information used to make UE 122 perform the first operation. In this case, for example, the first information may be included in an RRC message, a MAC control element, or a control PDU such as an SRAP layer or a PDCP layer, or may be received from the base station device by other signaling. The first operation may be transmitting second information to the base station device and/or a remote terminal device. The second information may be information indicating that successful delivery of RLC SDUs corresponding to one or more RLC sequence numbers has been confirmed by a lower layer (RLC layer).

As another example, in step S1000, the determination may be, for example, determining information on whether or not a condition is satisfied. In this case, for example, if UE 122 determines that the condition is satisfied in step S1000, the operation in step S1002 may be, for example, performing the first operation, or if UE 122 determines that the condition is not satisfied in step S1000, the operation in step S1002 may be, for example, not performing the first operation. The condition may be, for example, expiration of a first timer, and/or information on the transmission status of one or more SDUs or PDUs received from a lower layer (such as an RLC layer) being stored at or above a certain threshold. The first timer and/or the threshold may be set by the base station device via RRC signaling or system information, or may be set in advance. The UE 122 may restart the first timer in association with the first operation. The UE 122 may increment a first parameter by 1 based on receiving information about the transmission status of a certain RLC SDU from a lower layer (such as an RLC layer), or may reset the first parameter in association with the first operation. Also, based on the first parameter being equal to or greater than the threshold, the UE 122 may determine that information about the transmission status of one or more SDUs or PDUs received from a lower layer (such as an RLC layer) is stored above a certain threshold.

The UE 122 may be a terminal device that plays the role of a relay terminal device. For example, the Uu-SRAP of the UE 122 may be notified of successful delivery of the RLC SDU corresponding to a certain RLC sequence number from the Uu-RLC of the UE 122 that has received an ACK of the RLC SDU corresponding to the RLC sequence number from the Uu-RLC of a base station device, and in this case, the second information may be transmitted to the PC5-SRAP of a remote UE as the first operation. Similarly, the PC5-SRAP of the UE 122 may be notified of successful delivery of the RLC SDU corresponding to a certain RLC sequence number from the PC5-RLC of a remote terminal device, and in this case, the second information may be transmitted to the Uu-SRAP of a base station device as the first operation.

The remote terminal device, which has received the second information from the UE 122, may notify a higher layer (such as a PDCP layer) of successful delivery of an RLC SDU corresponding to one or more sequence numbers based on the second information. The notification may include information that enables the higher layer (such as a PDCP layer) to identify a packet (such as a PDCP SDU). In addition, the remote terminal device may receive a notification from a lower layer (such as an RLC layer) indicating successful delivery of an RLC SDU corresponding to a certain RLC sequence number, or, if the remote terminal device has not received the second information from the UE 122 but has received a notification from a lower layer (such as an RLC layer) indicating successful delivery of an RLC SDU corresponding to a certain RLC sequence number, the remote terminal device may notify a higher layer (PDCP layer) of successful delivery of an RLC SDU corresponding to a certain RLC sequence number based on expiration of a second timer associated with the RLC SDU. The base station device may perform an operation similar to that of the remote terminal device described above.

In each embodiment, the remote terminal device may be an L2 U2N Remote UE, and the relay terminal device may be an L2 U2N Relay UE. The remote terminal device and the relay terminal device may be called by names different from those described in each embodiment. In the example of this embodiment, the architecture of a U2N relay is illustrated, but the base station device, relay terminal device, and remote terminal device may be replaced with other devices.

When a terminal device that communicates with a base station device via a relay terminal device or the like performs a handover to a target cell or a target relay terminal device, the terminal device was unable to perform a handover without packet loss using conventional PDCP data recovery that presumes direct communication with the base station device. By using a method exemplified by one aspect of the present invention, it becomes possible to perform a handover without packet loss.

Furthermore, in each of the process examples or process flow examples in the above description, some or all of the steps may not be executed. Furthermore, in each of the process examples or process flow examples in the above description, the order of the steps may be different. Furthermore, in each of the process examples or process flow examples in the above description, some or all of the processes in each step may not be executed. Furthermore, in each of the process examples or process flow examples in the above description, the order of the processes in each step may be different. Furthermore, in the above description, "doing B based on A being true" may be rephrased as "doing B". In other words, "doing B" may be executed independently of "being A being true". Furthermore, in the above description, expressions such as "link", "associate", and "associate" may be used interchangeably.

In addition, in the above explanation, "A may be replaced with B" may mean replacing A with B, as well as replacing B with A. Also, in the above explanation, when it is written that "C may be D" and "C may be E", it may also mean that "D may be E". Also, in the above explanation, when it is written that "F may be G" and "G may be H", it may also mean that "F may be H".

In addition, in the above explanation, if condition "A" and condition "B" are contradictory conditions, condition "B" may be expressed as the "other" condition of condition "A."

The program that runs on the device related to this embodiment may be a program that controls a Central Processing Unit (CPU) or the like to cause a computer to function so as to realize the functions of this embodiment. The program or the information handled by the program is temporarily loaded into volatile memory such as Random Access Memory (RAM) during processing, or stored in non-volatile memory such as flash memory or a Hard Disk Drive (HDD), and is read, modified, and written by the CPU as necessary.

It should be noted that a part of the device in the above-mentioned embodiment may be realized by a computer. In that case, a program for realizing this control function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed to realize the control function. The "computer system" referred to here is a computer system built into the device, and includes hardware such as an operating system and peripheral devices. Furthermore, the "computer-readable recording medium" may be any of semiconductor recording media, optical recording media, magnetic recording media, etc.

Furthermore, "computer-readable recording medium" may include something that dynamically holds a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, or something that holds a program for a certain period of time, such as volatile memory within a computer system that serves as a server or client in such cases. The above program may also be one that realizes part of the functions described above, or one that can realize the functions described above in combination with a program already recorded in the computer system.

Furthermore, each functional block or feature of the device used in the above-mentioned embodiment may be implemented or executed by an electric circuit, typically an integrated circuit or a number of integrated circuits. The electric circuit designed to execute the functions described herein may include a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or a combination thereof. The general-purpose processor may be a microprocessor, or alternatively, the processor may be a conventional processor, controller, microcontroller, or state machine. The general-purpose processor or each of the aforementioned circuits may be composed of digital circuits or analog circuits. Furthermore, if an integrated circuit technology that replaces current integrated circuits emerges due to advances in semiconductor technology, it is also possible to use an integrated circuit based on that technology.

Note that this embodiment is not limited to the above embodiment. In the embodiment, an example of a device is described, but this embodiment is not limited to this, and can be applied to terminal devices or communication devices such as stationary or non-movable electronic devices installed indoors or outdoors, for example, AV equipment, kitchen equipment, cleaning/washing equipment, air conditioning equipment, office equipment, vending machines, and other household appliances.

Although this embodiment has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not depart from the gist of this embodiment are also included. Furthermore, this embodiment can be modified in various ways within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this embodiment. Also included are configurations in which elements described in the above embodiments are substituted for elements that achieve the same effect.

One aspect of the present invention can be used, for example, in a communication system, a communication device (e.g., a mobile phone device, a base station device, a wireless LAN device, or a sensor device), an integrated circuit (e.g., a communication chip), or a program, etc.

100 ng-eNB
102 gNB
110, 112, 114 Interface
122UE
200, 700 PHY
202, 702 MAC
204, 704 RLC
206, 706 PDCP
208, 708 RRC
210 PC5-S
310, 710 SDAP
400 Discovery
500, 600 receiver
502, 602 Processing section
504, 604 Transmitter
712 NAS
800 SRAP

Claims (3)

A terminal device that communicates with a base station device,
A receiving unit that receives signaling from the base station device;
A processing unit,
The processing unit performs Packet Data Convergence Protocol (PDCP) data recovery according to the signaling;
If the signaling includes a first parameter, performing a first configuration based on the signaling including the first parameter;
determining whether the first configuration is set, and if the PDCP data recovery determines that the first configuration is set, retransmitting all PDCP Protocol Data Units (PDUs) previously submitted to a Radio Link Control (RLC) entity;
Terminal device. A base station device that communicates with a terminal device,
A transmitting unit that transmits signaling to the terminal device;
A processing unit,
The processing unit causes the terminal device to perform Packet Data Convergence Protocol (PDCP) data recovery in accordance with the signaling;
causing a first configuration by including a first parameter in the signaling;
determining whether the first configuration is set, and causing the PDCP data recovery to determine that the first configuration is set, thereby causing a retransmission of all PDCP protocol data units (PDUs) previously submitted to a Radio Link Control (RLC) entity;
Base station equipment. A method for a terminal device communicating with a base station device, comprising:
receiving signaling from the base station;
performing Packet Data Convergence Protocol (PDCP) data recovery according to the signaling;
if the signaling includes a first parameter, performing a first configuration based on the signaling including the first parameter;
determining whether the first configuration is set, and if the PDCP data recovery determines that the first configuration is set, performing a retransmission of all PDCP Protocol Data Units (PDUs) previously submitted to a Radio Link Control (RLC) entity.
method.

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